I don't want to offend anyone, but from my experience I'd say that 50% of people don't know how to fill a cooler. A cooler, as in the big blue plastic things that hold beer and bottles of water and whatnot. A few points:
DO NOT put ice in the cooler first.
DO fill the cooler with everything that you're going to want in it.
DO fill it up good.
DO stand bottles of beer upright.
DO NOT put cans of beer in the cooler (you shouldn't be drinking beer from cans).
DO try to buy white wine with screw tops, as they are ideal for coolers.
DO fill the remaining space in the cooler with ice.
DO break up the large chunk of ice that comes out of that bag before putting it in the cooler.
DO have extra ice (ice, you know, melts) and place it in another cooler for later.
I won't get into the science behind this approach (the fact that cold air sinks, the fact that cold water comes from ice, and the fact that cold water sinks just like cold air). Just trust me.